Relaxation oscillators provide output signals at a particular frequency, often on the order of kilohertz or megahertz. Many relaxation oscillators provide output signals by dissipating energy stored in the relaxation oscillators, such as energy stored in one or more capacitors. For a number of applications, relaxation oscillators having a constant or nearly constant output frequency is desired.
The output frequency of a relaxation oscillator may depend on an amount of time for the relaxation oscillator to store a specified amount of energy, such as an amount of time to charge one or more capacitors of the relaxation oscillator. The output frequency of the relaxation oscillator may also depend on the delay associated with the operation of other components of the relaxation oscillator, such as the delay associated with the operation of one or more comparators, one or more flip-flops, and so on.
Certain relaxation oscillators attempt to achieve a constant output frequency by providing a constant current to store energy in the relaxation oscillators in order to achieve a constant time needed to charge the relaxation oscillator. Additionally, many relaxation oscillators attempt to provide a constant output frequency by minimizing the delay associated with the operation of the other components of the relaxation oscillator. However, even when the time to store energy in the relaxation oscillator is constant or nearly constant, the delay associated with the operation of components of the relaxation oscillator can still cause unacceptable changes in the output frequency, especially as the output frequency increases and the supply voltage varies. Furthermore, many relaxation oscillators utilize expensive and technologically advanced components in an attempt to minimize the delay of these components, but these components often increase power consumption associated with the relaxation oscillator.